TW201509949A - Compositions for photo-alignment layers - Google Patents

Abstract

The invention is a composition for a photo-alignment film, which contains a compound (A1) and an organic solvent (B), or contains a polymer (A2) and an organic solvent (B), wherein the compound (A1) is obtained from a reaction of at least one acid anhydride (a1) selected from a group of a compound represented by Formula (1) and Formula (2), and a compound (a2) having an amino group and an alkoxysilyl group in a molecule, the polymer (A2) is obtained by polymerizing the compound (A1). A liquid crystal alignment film formed by the composition of the invention has a high photo-alignment sensitivity after firing at a high temperature, excellent adhesion with a basis, and is soluble in an alcohol-typed solvent (wherein a flexible substrate is not corrosive), and then may be produced cheaply. In the Formulas, R1, R2 and R3 respectively and independently are a hydrogen or an alkyl group having a carbon quantity ranging from 1 to 5.

Description

Light alignment film composition

The present invention relates to a composition for a photo-alignment film, a photo-alignment film formed using the composition, and an optical film or a liquid crystal display element using the same.

The liquid crystal display element is a view finder and projection applied to a video camera as a representative of a note personal computer or a desktop personal computer monitor. Various types of liquid crystal display devices such as a display and a television. Further, it can also be used as an optoelectronics-related element such as an optical printer head, an optical Fourier transform element, or a light bulb. The mainstream of the conventional liquid crystal display device is a display element using a nematic liquid crystal, and the twist direction of the alignment direction of the liquid crystal in the vicinity of one substrate and the alignment direction of the liquid crystal in the vicinity of the other substrate is reversed at an angle of 90°. Twisted Nematic (TN) mode, super-twisted nematic direction in which the alignment direction is usually twisted at an angle of 180° or more (Super Twisted Nematic, STN) mode, liquid crystal display elements such as In Plane Switching (IPS) mode and Fringe Field Switching (FFS) mode in which the alignment direction is aligned with the substrate horizontally aligned application.

However, the liquid crystal display elements have a narrow viewing angle capable of properly viewing an image, a case where brightness or contrast is lowered when viewed from an oblique direction, and a brightness inversion with halftone (halftone). Happening. In recent years, the problem of this viewing angle is a multi-domain vertical alignment (MVA) mode using a TN type liquid crystal display element using an optical compensation film and a technique of using a vertical alignment and a protrusion structure (refer to Patent Document 1). It is improved by the IPS (In-Plane Switching) mode of the transverse electric field type (refer patent document 2).

The development of the technology of liquid crystal display elements is achieved not only by improving the driving modes or component configurations, but also by improving the components for the display elements. Among the members for display elements, in particular, the liquid crystal alignment film is one of the important factors related to the display quality of the liquid crystal display element, and the role of the liquid crystal alignment film becomes important year by year with the improvement of the quality of the display element.

For the liquid crystal alignment film, in order to uniform display characteristics of the liquid crystal display element, it is necessary to uniformly control the molecular arrangement of the liquid crystal. Therefore, it is required to uniformly align liquid crystal molecules on the substrate in one direction.

In addition, in order to improve the contrast of the image display device or to expand the viewing angle range, for example, a film having a refractive index anisotropy or a film obtained by polymerizing a polymerizable liquid crystal compound to form a compound is used as an optical compensation film. Or bit Phase difference film. In order to align the polymerizable liquid crystalline compound, a liquid crystal alignment film is also used. The liquid crystal alignment film in which the directions of the liquid crystal molecules on the substrate are uniformly arranged can be utilized in various occasions in the manufacturing steps of the liquid crystal display element, and this technique is important and indispensable.

The liquid crystal alignment film can be prepared using a liquid crystal alignment agent. At present, the liquid crystal alignment agent mainly used is a solution of polylysine or a soluble polyimine dissolved in an organic solvent. After applying such a solution to a substrate, a film is formed by heating or the like to form a polyimide film of a polyimine-based liquid crystal alignment film. Various liquid crystal alignment agents other than polyglycolic acid have also been studied, but in terms of heat resistance, chemical resistance (liquid crystal resistance), coating properties, liquid crystal alignment, electrical properties, optical properties, display characteristics, and the like, It is almost impossible to achieve practical application.

Industrially, a rubbing method that can easily perform high-speed processing on a large area is widely used as an alignment treatment method. The rubbing method is a process of rubbing the surface of the liquid crystal alignment film in one direction by using a cloth obtained by flocking fibers such as nylon, ruthenium, or polyester, whereby uniform alignment of liquid crystal molecules can be obtained. However, since the rubbing method generates dust or static electricity, there is a problem that alignment defects and the like affect the liquid crystal element.

Therefore, in recent years, a liquid crystal alignment control method has been developed instead of the rubbing method. A plurality of alignment methods such as a photodecomposition method, a photoisomerization method, a photodimerization method, and a photocrosslinking method have been proposed for the photo-alignment method in which the alignment treatment is performed by irradiation (see Non-Patent Document 1, Patent Document 3, and Patent Literature). 4). The light alignment method is different from the friction method in that it is a non-contact alignment method, and in principle, the generation of dust or static electricity is less than the friction treatment.

Good alignment by using the alignment method using the photo-alignment method The liquid crystal alignment film can control the molecular alignment state of the liquid crystal monolayer contacting the liquid crystal alignment film, and is easy to perform alignment division. Thus, improvement in performance as a liquid crystal display element can be expected.

A compound which can be used for the photo-alignment method is a polymer having a photoreactive cinnamate bonded to a side chain of a copolymer (see Patent Document 5 and Patent Document 6). However, this system has a large decrease in the liquid crystal alignment ability when calcined at a high temperature, and there are cases in which the substrate adhesion is problematic. Further, the solvent for dissolving the polymers must have a solvent having a high dissolving power, and in particular, in the case of a flexible plastic substrate, it is difficult to use the substrate by etching the substrate. On the other hand, since a monomer having a specific structure is synthesized and then polymerized, there is also a problem that the cost becomes high.

On the other hand, a siloxane compound having a maleimide structure has been proposed as a composition for photocuring (see Patent Document 7). However, Patent Document 7 does not describe any photo-alignment of a liquid crystal compound.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent No. 2947350

[Patent Document 2] Japanese Patent No. 2940354

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2005-275364

[Patent Document 4] Japanese Patent Laid-Open No. 11-15001

[Patent Document 5] Japanese Patent No. 3161342

[Patent Document 6] Japanese Patent No. 4011652

[Patent Document 7] Japanese Patent No. 2630596

[Non-patent literature]

[Non-Patent Document 1] Liquid Crystal, Vol. 3, No. 4, edited by the Editorial Board of the Japanese Society of Liquid Crystals, issued by the Japanese Society of Liquid Crystals, 1999, p. 262 (page)

An object of the present invention is to provide a composition for a photo-alignment film suitable for a photo-alignment method. Specifically, an object of the present invention is to provide an alcohol-based solvent which is excellent in optical alignment sensitivity after high-temperature calcination, has excellent adhesion to a substrate, and is soluble in a flexible substrate (which does not attack a flexible substrate), and is therefore inexpensive. A liquid crystal alignment film manufactured by the ground.

As a result of intensive research and development, the present inventors have achieved a liquid crystal alignment film which can achieve the above object by using a specific composition for a photo-alignment film.

The present invention encompasses the following items.

[1] A composition for a photo-alignment film comprising at least one acid anhydride (a1) selected from the group consisting of compounds represented by formula (1) and formula (2), and an amine group and an alkoxy group in the molecule. a compound (A1) obtained by reacting a decyl group-containing compound (a2) and an organic solvent (B), or a polymer (A2) obtained by polymerizing the compound (A1) and an organic solvent (B),

In the formula, R ¹ , R ² and R ³ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms.

[2] The composition for a photo-alignment film according to [1], wherein the acid anhydride (a1) is at least one selected from the group consisting of maleic anhydride, itaconic anhydride, and citraconic anhydride.

[3] The composition for a photo-alignment film according to [1] or [2], wherein the compound (a2) having an amine group and an alkoxyalkyl group in the molecule is selected from the group consisting of 3-aminopropyltrimethyl At least one of oxoxane, 3-aminopropyltriethoxydecane, 4-aminophenyltrimethoxydecane, and 4-aminophenyltriethoxydecane.

[4] A photo-alignment film produced by using the photocurable composition according to any one of [1] to [3].

[5] A display element produced by using the photo alignment film according to [4].

In the present invention, since the liquid crystal alignment film is formed using the compound having a photoreactive group, the complicated processing steps which are seen in the conventional rubbing treatment can be omitted, and the alignment defects caused by dust or static electricity generated at this time are not generated. Therefore, a liquid crystal alignment film having high optical uniformity can be obtained. Further, an optical film or a liquid crystal display element produced by using the liquid crystal alignment film can maintain high alignment stability.

The composition for a photo-alignment film of the present invention contains at least one acid anhydride (a1) selected from the group consisting of the compounds represented by the following formulas (1) and (2), and an amine group and an alkoxydecane in the molecule. The compound (A1) obtained by the reaction of the compound (a2) and the organic solvent (B) in which it is dissolved, or the polymer (A2) obtained by polymerizing the compound (A1) and an organic solvent (B) obtained by dissolving the compound (A2) ). The compound (A1) is a photopolymerizable group (m-butylene imine, citrate, imine) obtained by reacting the acid anhydride (a1) and the compound (a2) in detail. A silane coupling agent. The polymer (A2) is specifically a siloxane polymer having a polymerizable group (m-butyleneimine, cimolimide, and itaconide) obtained by polycondensing the compound (A1). Hereinafter, the compounds, polymers, solvents, and other various elements constituting the present invention will be described.

1. Anhydride (a1)

The acid anhydride (a1) is at least one selected from the group consisting of compounds represented by the following formulas (1) and (2).

In the formula, R ¹ , R ² and R ³ are each independently hydrogen and an alkyl group having 1 to 5 carbon atoms.

Specific examples of the acid anhydride (a1) are maleic anhydride, itaconic anhydride, citraconic anhydride, and 2,3-dimethyl maleic anhydride. The acid anhydride (a1) may be used alone or in combination of two or more.

2. A compound having an amine group and an alkoxyalkyl group in the molecule (a2)

Specific examples of the compound (a2) having an amino group and an alkoxyalkyl group in the molecule are 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, and 3-aminopropyldiamide. Methoxymethyl decane, 3-aminopropyl diethoxymethyl decane, 4-aminophenyl trimethoxy decane, 4-aminophenyl triethoxy decane, N-2- (amine Benzyl)-3-aminopropyltrimethoxydecane, and N-2-(aminoethyl)-3-aminopropyltriethoxydecane. More preferred compound (a2) is 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 3-aminopropyldimethoxymethylnonane, and 3-amino group. Preference is given to propyldiethoxymethyldecane, and further preferred compound (a2) is 3-aminopropyltrimethoxydecane and 3-aminopropyltriethoxydecane.

3. Compound (A1)

The acid anhydride (a1) and the compound (a2) are easily reacted by stirring at room temperature in a solvent to form proline. Thereafter, the proline acid is heated to imidize it to obtain the compound (A1). The heating temperature at the time of hydrazine imidization is 60 ° C to 150 ° C, preferably 80 ° C to 130 ° C. An alkali catalyst can also be added as a ruthenium-based catalyst. Examples of the base catalyst are pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Further, the polymerization for suppressing the photopolymerizable group caused in the reaction is For the purpose, a polymerization inhibitor may also be used in combination. Examples of polymerization inhibitors are 2,2,6,6-tetramethylpiperidinyl-1-oxyl radical, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxo free Base, triphenylverdazyl, p-methoxyphenol, and hydroquinone.

The solvent to be used in the reaction of the synthesis of the compound (A1) is not particularly limited as long as it can dissolve the acid anhydride (a1), the compound (a2) and the compound (A1) obtained as a raw material. However, when it is necessary to suppress the hydrolysis condensation of the alkoxyalkyl group moiety of the compound (A1), it is preferred to use a solvent having a hydroxyl group and to synthesize it at a low concentration and at a low temperature. By setting the heating temperature to 60 ° C to 80 ° C, it is possible to suppress the formation of a polymer due to the reaction of the alkoxyalkyl group moiety, thereby obtaining the compound (A1) in a high yield.

4. Polymer (A2)

The obtained compound (A1) can be used as it is in the composition for a photo-alignment film of the present invention, but if it is used in the form of a polymer, uniform optical alignment can be easily obtained by various coating methods. The film is therefore better. In order to obtain the polymer (A2) by polymerizing the compound (A1), hydrolysis and condensation of the alkoxyalkyl group moiety are necessary. To the compound (A1), an acid catalyst such as water or formic acid is added and further heated, and the low boiling component is distilled off, whereby the polymer (A2) can be obtained. The heating temperature in the reaction is preferably from 90 ° C to 150 ° C.

In addition, if the compound (A1) is synthesized at a high concentration. When heated at a high temperature, the proline acid produced in the initial reaction itself acts as an acid catalyst, and the hydrolysis reaction of the alkoxyalkyl group is caused by the use of water produced by the imidization of guanidine acid. Therefore, the polymer (A2) can also be obtained in one stage. Heating during the reaction The temperature is preferably from 100 ° C to 150 ° C.

The solvent used in the polymerization reaction is not particularly limited as long as it can dissolve the polymer (A2). When formic acid or water is added as a catalyst, the hydrolysis condensation reaction can be further carried out.

The polymer (A2) is a siloxane polymer having a photopolymerizable group and has a weight average molecular weight of 500 to 1,000,000. The weight average molecular weight is preferably from 1,000 to 500,000, and more preferably from 2,000 to 100,000 from the viewpoint of easiness of filtration, storage stability, and light alignment ability.

5. Organic solvent (B)

The organic solvent (B) is an organic solvent capable of dissolving the acid anhydride (a1) and the compound (a2) and dissolving the compound (A) obtained by reacting (a1) with (a2), by spin coating. In the case of forming a photo-alignment film such as a slit coat or another printing method, it is preferred to apply an organic solvent having high uniformity. Further, when the substrate is a flexible substrate, in order to avoid erosion of the substrate, an alcohol solvent is preferably used.

Examples of the organic solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, acetone, 2-butanone, and ethyl acetate. , propyl acetate, tetrahydrofuran, acetonitrile, dioxane, toluene, xylene, cyclopentanone, cyclohexanone, diacetone alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol single Methyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, methyl 3-methoxypropionate, and ethyl 3-ethoxypropionate, N - Methyl pyrrolidone, γ-butyrolactone.

From the viewpoint of coatability, storage stability, and avoidance of erosion of the substrate, an organic solvent having a hydroxyl group is more preferable. Specific examples thereof are ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, diacetone alcohol, ethylene glycol monoethyl ether, and ethylene glycol monobutylene. Ether, propylene glycol monomethyl ether, diethylene glycol monoethyl ether. Among them, propylene glycol monomethyl ether and diacetone alcohol having a moderate boiling point are further preferred.

6. Other ingredients

The composition for a photo-alignment film of the present invention may further contain other components than the compound (A1), the polymer (A2), and the organic solvent (B) insofar as the effects of the present invention are obtained. For example, in order to improve coating uniformity, film hardness, and adhesion, various additives may be added to the composition for a photo-alignment film of the present invention. Examples of such an additive include acrylic acid, styrene-based, polyethyleneimine-based or urethane-based polymer dispersants, anionic, cationic, nonionic or fluorine-based surfactants, and hydrazine. A coating improver, a hindered phenol type, a hindered amine type, an antioxidant such as a phosphorus-based compound or a sulfur-based compound, an adhesion improver such as a coupling agent, a thermal crosslinking agent such as an epoxy compound, or a photoradical initiator. A radical generating agent such as a thermal radical initiator or a sensitizer.

6-1. Polymer dispersant, surfactant, and coating improver

For the polymer dispersant, the surfactant, and the coatability improver, the components used in these applications can be used in the composition. These may be one type or two or more types. Examples of such a polymer dispersant, a surfactant, and a coatability improver include, for example, POLYFLOW No. 45, POLYFLOW KL-245, POLYFLOW No. 75, POLYFLOW No. 90, and POLYFLOW No. above 95, All are trade names, manufactured by Kyoei Chemical Industry Co., Ltd.), Disperbyk 161, Disperbyk 162, Disperbyk 163, Disperbyk 164, Disperbyk 166, Disperbyk 170, Disperbyk 180, Disperbyk 181, Disperbyk 182, BYK300, BYK306, BYK310, BYK320, BYK330, BYK342, BYK344, BYK346, BYK361N (all of which are trade names, manufactured by BYK-Chemie Japan Co., Ltd.), KP-341, KP-358, KP -368, KF-96-50CS, KF-50-100CS (above, all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.), Surflon SC-101, Surflon KH-40 (above, all Trade name, manufactured by Seimi Chemical Co., Ltd., Ftergent 222F, Ftergent 251, FTX-218 (all of which are trade names, manufactured by NEOS), Ai EFTOP EF-351, EFTOP EF-352, EFTOP EF-601, EFTOP EF-801, EFTOP EF-802 (all of which are trade names, manufactured by Mitsubishi Materials Co., Ltd.), Meijiafa (Megafac) F-171, Megafac F-177, Megafac F-475, Mega Fac R-08, Megafac R-30 (above, all trade names, manufactured by Di Ai Sheng (DIC) Co., Ltd.), fluoroalkylbenzenesulfonate, fluoroalkyl carboxylate, fluoroalkyl polyoxyethylene ether , fluoroalkyl ammonium iodide, fluoroalkyl betaine, fluoroalkyl sulfonate, diglycerol tetra (fluoroalkyl polyoxyethylene ether), fluoroalkyl trimethyl ammonium salt, fluoroalkyl amino sulfonic acid Salt, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether , polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene laurate, polyoxyethylene oleate, polyoxyethylene Stearate, polyoxyethylene laurylamine, sorbitan laurate, sorbitan palmitate, sorbitan stearate, sorbitan oleate, sorbitan fat Acid ester, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan oleate, polyoxygen Vinyl naphthyl ether, alkylbenzene sulfonate, and alkyl diphenyl ether disulfonate.

Among these, from the viewpoint of improving the uniformity of coating of the composition for photo-alignment film of the present invention, it is preferred that the additive contains a fluoroalkylbenzenesulfonate or a fluoroalkylcarboxylate selected from the group consisting of fluoroalkylbenzenesulfonate and fluoroalkylcarboxylate. , fluoroalkyl polyoxyethylene ether, fluoroalkyl ammonium iodide, fluoroalkyl betaine, fluoroalkyl sulfonate, diglycerol tetra (fluoroalkyl polyoxyethylene ether), fluoroalkyl trimethyl ammonium salt And a fluorine-based surfactant such as a fluoroalkylaminosulfonate, and a group of lanthanide coating improvers such as BYK306, BYK342, BYK344, BYK346, KP-341, KP-358, and KP-368 At least one of the groups.

The content of the polymer dispersant, the surfactant, and the coatability improver in the composition for a photo-alignment film of the present invention is preferably 0.001 part by weight per 100 parts by weight of the total solid content of the composition. ~0.1 parts by weight.

6-2. Antioxidants

Among the antioxidants, an antioxidant of a hindered phenol type, a hindered amine type, a phosphorus type, and a sulfur type compound can be preferably used. The antioxidant may be one type or two or more types. From the viewpoint of weather resistance, the antioxidant is preferably an antioxidant of a hindered phenol compound. Examples of such an antioxidant include Irganox 1010, Irganox FF, Irganox 1035, Irganox 1035FF, Irganox 1076, Irganox 1076FD, Irganox 1076DWJ, Irganox 1098, Irganox 1135, Irganox 1330, Irganox 1726, Irganox 1425 WL, Irganoxl 520L, Irganox 245, Irganox 245FF, Irganox 245DWJ, Irganox 259, Irganox 3114, Irganox 565, Irganox 565DD, Irganox 295 (above, both Product name; manufactured by BASF Japan Co., Ltd., ADK STAB AO-20, ADK STAB AO-30, ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-70, and ADK STAB AO- 80 (above, all are trade names; manufactured by ADEKA Co., Ltd.). Among them, ADK STAB AO-60 is more preferable.

The content of the antioxidant in the composition for a photo-alignment film of the present invention is preferably 0.1 part by weight to 5 parts by weight, more preferably 1 part by weight to 3 parts by weight, per 100 parts by weight of the compound (A).

6-3. Adhesion improver

The adhesion improving agent is for improving the adhesion between the composition for a photo alignment film and the substrate. A coupling agent can be preferably used in the adhesion improving agent. The adhesion improving agent may be one type or two or more types. A decane-based, aluminum-based or titanate-based compound can be used as the coupling agent. Examples of such a coupling agent include 3-glycidoxypropyldimethylethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltrimethoxy. Base decane, acetonitrile alkoxy aluminum diisopropoxide, and tetraisopropyl bis (dioctyl phosphite) titanate. Among these, 3-glycidoxypropyltrimethoxydecane is preferred because it has a large effect of improving adhesion.

The content of the adhesion improving agent in the composition for a photo-alignment film of the present invention is preferably 10 parts by weight or less based on 100 parts by weight of the compound (A).

6-4. Thermal crosslinking agent

As the thermal crosslinking agent, a component which causes a crosslinking reaction under heating conditions at the time of film formation using a composition for a photo-alignment film can be used. The thermal crosslinking agent may be one type or two or more types. A thermal crosslinking agent such as an epoxy compound may be used for the thermal crosslinking agent, and examples of such a thermal crosslinking agent include Epikote 807, Epikote 815, Epikote 825, Epikote 827, Epikote 828, and Epikote 190P. Epikote 191P, Epikote 1004, Epikote 1256, YX 8000 (all of which are trade names; Japan Epoxy Resin Co., Ltd.), Araldite CY177, Araldite CY184 (all of which are trade names) ; manufactured by BASF Corporation of Japan), Celloxide 2021P, EHPE-3150 (all of which are trade names; manufactured by Daicel Chemical Industries Co., Ltd.), and Techmore VG3101L ( Trade name; manufactured by Printech Co., Ltd.).

The content of the thermal crosslinking agent in the composition for a photo-alignment film of the present invention is preferably from 1 part by weight to 30 parts by weight, more preferably from 5 parts by weight to 15 parts by weight per 100 parts by weight of the solid content of the composition. Share.

6-5. Free radical generator. Sensitizer

The photoradical generator may, for example, be 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 1173), 1-hydroxycyclohexyl phenyl ketone, 2,2-di Methoxy-1,2-diphenylethane-1-one (IRGACURE 651), 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE 184), IRGACURE 127, IRGACURE 500 (IRGACURE a mixture of 184 and benzophenone), IRGACURE 2959, IRGACURE 907, IRGACURE 369, IRGACURE 379, IRGACURE 754, IRGACURE 1300, IRGACURE 819, IRGACURE 1700, IRGACURE 1800, IRGACURE 1850, IRGACURE 1870, DAROCUR 4265, DAROCUR MBF, DAROCUR TPO, IRGACURE 784, IRGACURE 754, IRGACURE OXE01, and IRGACURE OXE02. The DAROCUR and IRGACURE are all trade names of BASF Corporation of Japan. A known sensitizer (isopropyl thioxanthone, diethyl thioxanthone, ethyl 4-dimethylaminobenzoate (DAROCUR EDB), 4-dimethyl group may also be added to the above. 2-ethylhexyl benzoate (DAROCUR EHA), 4,4'-dimethylaminobenzophenone (NISSOCURE MABP manufactured by Nippon Soda Co., Ltd.), 4,4'-diethylamine Dialkylaminobenzophenone, etc., such as benzophenone (EAB manufactured by HODOGAYA CHEMICAL Co., Ltd.).

The thermal radical generating agent is exemplified by 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70 manufactured by Wako Pure Chemical Industries Co., Ltd.), 2, 2'-Azobis(2,4-dimethylvaleronitrile) (V-65 manufactured by Wako Pure Chemical Industries, Ltd.), 2,2'-azobis(isobutyronitrile) (Wako Pure Chemical Industries, Ltd.) V-60), 2,2'-azobis(2-methylbutyronitrile) manufactured by Co., Ltd. (V-59 manufactured by Wako Pure Chemical Industries Co., Ltd.), 2,2'-azobis [ N-(2-propenyl)-2-methylpropanamide] (VF-096, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2'-azobis(N-butyl-2-methyl) Propylamine) (VAm-110 manufactured by Wako Pure Chemical Industries Co., Ltd.), 2,2'-azobis(dimethyl isobutyrate) (V-601 manufactured by Wako Pure Chemical Industries, Ltd.).

2. The radical initiator in the composition for photoalignment film of the present invention. increase The content of the sensate is preferably from 0.1 part by weight to 10 parts by weight, more preferably from 1 part by weight to 10 parts by weight, even more preferably from 3 to 10 parts, per 100 parts by weight of the solid component of the composition.

7. Storage conditions of components for photoalignment film

The composition for a photo-alignment film of the present invention is preferably light-shielded and stored in a temperature range of -30 ° C to 25 ° C from the viewpoint of the stability of the composition for a photo-alignment film. When the storage temperature is -20 ° C to 10 ° C, it is more preferable from the viewpoint of preventing the occurrence of precipitates from the photosensitive composition.

8. Film formation of optical alignment film and alignment evaluation of polymerizable liquid crystal

Hereinafter, the method of forming the photoalignment film and the evaluation of the alignment of the polymerizable liquid crystal as a material aligned on the photoalignment film will be described.

8-1. Film formation method of light alignment film

The composition for photoalignment film of the present invention is applied onto a substrate by a known method such as spin coating, roll coating or slit coating. Examples of the substrate include a transparent glass substrate such as white plate glass, blue plate glass, and cyan coated glass coated with cerium oxide, polycarbonate, polyether oxime, polyester, acrylic acid, vinyl chloride, aromatic polyamide, and poly A synthetic resin sheet such as a melamine imide or a polyimide, a metal substrate such as a film or a substrate, an aluminum plate, a copper plate, a nickel plate, or a stainless steel plate, another ceramic plate, and a semiconductor substrate having a photoelectric conversion element. For these substrates, pretreatment such as chemical treatment such as decane coupling agent, plasma treatment, ion plating, sputtering, gas phase reaction, and vacuum vapor deposition may be performed.

Next, the coating film of the photo-alignment film composition on the substrate is dried by a hot plate or an oven. Usually, it is dried at 60 ° C ~ 150 ° C for 1 minute ~ 5 minutes. The film thickness of the photo-alignment film is not particularly limited, and the film thickness is usually about 1 nm to 300 nm. Light irradiated from a light irradiation device such as an ultrahigh pressure mercury lamp is converted into polarized light by a polarizing plate such as a wire grid, and is irradiated onto the light alignment film on the dried substrate. The irradiation amount is preferably about 1 mJ/cm ² to 3,000 mJ/cm ² at a wavelength of 300 nm to 450 nm.

8-2. Orientation evaluation method of polymerizable liquid crystal

First, a polymerizable liquid crystal composition for evaluation was prepared in the following manner. Addition of LC 242 (trade name, manufactured by BASF Corporation of Japan) 5.0 g, IRGACURE 907 (trade name, manufactured by BASF Corporation, Japan) 0.25 g, BYK 361N (trade name, manufactured by Nippon Chemical Co., Ltd.) 0.0050 g Further, toluene was added as an organic solvent so that the organic solvent became 85 wt% of the whole, and the mixture was uniformly dissolved and dissolved. This composition was made into the polymerizable liquid crystal composition (1).

8-2-1. Pre-bake (pre-bake) light alignment sensitivity

The polymerizable liquid crystal composition (1) was formed on a substrate coated with a polarized light-aligning film by a coating method such as spin coating, and dried on a hot plate at 80 ° C for 1 minute. After cooling the substrate to room temperature, the polymer liquid crystal composition is photocured by irradiation with light such as an ultrahigh pressure mercury lamp to fix the alignment. The substrate after photohardening of the produced polymerizable liquid crystal was sandwiched between two polarizing plates in an orthogonal (cross nicol) state, and a backlight was irradiated from below to observe. Polymeric fluid When the crystal is horizontally aligned, if the substrate is rotated, the bright and dark states can be alternately observed. The minimum exposure amount that can be displayed in the light and dark without the alignment defect (light leakage) is "the light alignment sensitivity after prebaking".

8-2-2. Post-bake (post-baking) light alignment sensitivity

The photoalignment film was spin-coated on the glass substrate in the same manner as described above, dried at 130 ° C for 5 minutes, and further baked at 230 ° C for 30 minutes. Thereafter, the light irradiated from the ultrahigh pressure mercury lamp is converted into linear polarized light by a filter that cuts off light of 300 nm or less and a wire grid polarizing plate, and the glass substrate coated with the photoalignment film is irradiated with 10 mJ/cm ^{2 .} (value at 313 nm). Next, the polymerizable liquid crystal composition (1) was spin-coated on the substrate at 1300 rpm for 10 seconds, and dried on a hot plate at 80 ° C for 1 minute. After cooling the substrate to room temperature, the light of an ultrahigh pressure mercury lamp of 300 mJ/cm ² (a value at 313 nm) was irradiated to photoharden the polymerizable liquid crystal composition to fix the alignment. The substrate after photohardening of the produced polymerizable liquid crystal was sandwiched between two polarizing plates in a cross nicol state, and the backlight was irradiated from below to observe. When the polymerizable liquid crystal is horizontally aligned, when the substrate is rotated, a state of light and dark can be alternately observed. The minimum exposure amount that can be displayed in the light and dark without the alignment defect (light leakage) is "the post-baking light alignment sensitivity".

8-3. Evaluation method of substrate adhesion

The cross-cut test was performed using the substrate after the polymerization liquid crystal immobilization prepared in the evaluation of the optical alignment sensitivity described above. A 100 mm mass slit was formed using a cutter and a cross cut guide, and an adhesive tape was attached from the upper side and peeled off. This evaluates the adhesion. In the case where 100 pieces of the tape were not peeled off, the case where no peeling occurred was set to ◎, and when 80% or more of the tape was not peeled off, it was set to ○, and the following was set to ×. The test was carried out using both the substrate after the pre-bake optical alignment sensitivity test and the substrate after the post-baking photoalignment sensitivity test.

[Examples]

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited by the examples.

[Synthesis Example 1] Synthesis of Compound (A1)

Propylene glycol monomethyl ether as a polymerization solvent, maleic anhydride as the compound (a1), and 3-amino group as the compound (a2) were added to a flask with a stirrer in a flask with four necks. Propyltriethoxysilane, dibutylhydroxytoluene as a polymerization inhibitor. The four-necked flask was heated in an oil bath set at 100 ° C for 1 hour, further set to 120 ° C for 2 hours, and the low-boiling component was distilled off under normal pressure.

The concentrated reaction solution was cooled to room temperature and recovered, to obtain a compound (A1) solution having a solid concentration of 40% by weight. Here, the solid content concentration is determined by the dry weight method. The assay is as follows. A small amount of the compound (A1) solution was applied to a 40 mm × 40 mm square glass substrate by a bar coater. The initial weight W1 was measured. Thereafter, the glass substrate was dried by a hot plate at 100 ° C for 5 minutes, and the weight W2 was measured again. Finally, the solid content concentration of the compound (A1) solution was calculated by (W2/W1) × 100.

A portion of the solution was sampled and the weight average molecular weight was determined by Gel Permeation Chromatography (GPC) analysis (polystyrene standard). In the GPC analysis, polystyrene (VARIAN (Varian) made polystyrene calibration kit PL2010-0102) having a molecular weight of 645 to 132,900 was used as the standard polystyrene, and the column was used. PLgel MIXED-D (manufactured by VARIAN Co., Ltd.), the mobile phase was measured using tetrahydrofuran (THF), and the column temperature was set to 35 ° C using a differential refractive index detector. As a result, the weight average molecular weight of the compound (A1) was 3,200.

[Synthesis Example 2] Synthesis of Compound (A2)

Propylene glycol monomethyl ether as a polymerization solvent, citraconic anhydride as the compound (a1), and 3-aminopropyltriethoxysilane as the compound (a2) were added to a four-necked flask equipped with a stirrer in the following manner. The four-necked flask was heated in an oil bath set to 100 ° C for 1 hour, further set to 120 ° C for 2 hours, and the low-boiling component was distilled off under normal pressure.

A solution of the compound (A2) was obtained by the method according to Synthesis Example 1. The solid content concentration of the compound (A2) determined by the dry weight method was 41% by weight, and GPC analysis was carried out in the same manner. As a result, the weight average molecular weight of the compound (A2) was 2,600.

[Synthesis Example 3] Synthesis of Compound (A3)

Propylene glycol monomethyl ether as a polymerization solvent, itaconic anhydride as the compound (a1), and 3-aminopropyltriethoxysilane as the compound (a2) were added to a four-necked flask equipped with a stirrer in the following manner. The four-necked flask was heated in an oil bath set to 100 ° C for 1 hour, further set to 120 ° C for 2 hours, and the low-boiling component was distilled off under normal pressure.

The compound (A3) solution was obtained by the method according to Synthesis Example 1. The solid content concentration of the compound (A3) determined by the dry weight method was 43% by weight, and GPC analysis was carried out in the same manner. As a result, the weight average molecular weight of the compound (A3) was 3,000.

[Synthesis Example 4] Synthesis of Compound (A4)

Propylene glycol monomethyl ether as a polymerization solvent, citraconic anhydride as the compound (a1), and 3-aminopropyltriethoxysilane as the compound (a2) were added to a four-necked flask equipped with a stirrer in the following manner. The four-necked flask was heated in an oil bath set to 100 ° C for 1 hour, further set to 120 ° C for 2 hours, and the low-boiling component was distilled off under normal pressure.

Thereafter, the reaction liquid was temporarily cooled to about room temperature, and then 3.39 g of formic acid and 4.82 g of water were added to the reaction liquid. The oil bath temperature was again set to 100 ° C for 1 hour, and further set to 120 ° C for 2 hours, and the low boiling component was distilled off under normal pressure.

The compound (A4) solution was obtained by the method according to Synthesis Example 1. The solid content concentration of the compound (A4) determined by the dry weight method was 39% by weight, and GPC analysis was carried out. As a result, the weight average molecular weight of the compound (A4) was 5,800.

[Synthesis Example 5] Synthesis of Compound (A5)

Propylene glycol monomethyl ether as a polymerization solvent, itaconic anhydride as the compound (a1), and 3-aminopropyltriethoxysilane as the compound (a2) were added to a four-necked flask equipped with a stirrer in the following manner. The four-necked flask was heated in an oil bath set to 100 ° C for 1 hour, further set to 120 ° C for 2 hours, and the low-boiling component was distilled off under normal pressure.

Thereafter, the reaction liquid was temporarily cooled to about room temperature, and then 3.39 g of formic acid and 4.82 g of water were added to the reaction liquid. Again set the oil bath temperature to 100 ° C and react 1 small At this time, it was further set to aging at 120 ° C for 2 hours, and the low boiling component was distilled off under normal pressure.

A solution of the compound (A5) was obtained by the method according to Synthesis Example 1. The solid content concentration of the compound (A5) determined by the dry weight method was 42% by weight, and GPC analysis was carried out. As a result, the weight average molecular weight of the compound (A5) was 6,000.

[Synthesis Example 6] Synthesis of Compound (A6)

Propylene glycol monomethyl ether as a polymerization solvent, maleic anhydride as a compound (a1), and citraconic anhydride, and 3-aminopropyl group as the compound (a2) were added to a four-necked flask equipped with a stirrer in the following weight. Triethoxy decane, dibutylhydroxytoluene as a polymerization inhibitor. The four-necked flask was heated in an oil bath set to 100 ° C for 1 hour, further set to 120 ° C for 2 hours, and the low-boiling component was distilled off under normal pressure.

The compound (A6) solution was obtained by the method according to Synthesis Example 1. The solid content concentration of the compound (A6) determined by the dry weight method was 39% by weight, and GPC analysis was carried out. As a result, the weight average molecular weight of the compound (A6) was 2,700.

[Comparative Synthesis Example 1] Synthesis of Polymer (E1)

A ring as a polymerization solvent was added to a four-necked flask equipped with a stirrer with the following weight Pentanone, monomer of the following formula (e1), 2,2'-azobis(methyl 2-methylpropionate) (V-601 manufactured by Wako Pure Chemical Industries, Ltd.), at 80 ° C for 3 hours Radical polymerization gave a polymer (E1) solution having a solid concentration of 30% by weight.

GPC analysis was carried out by the method according to Synthesis Example 1. As a result, the weight average molecular weight of the polymer (E1) was 9,500.

[Examples 1 to 6] and [Comparative Example 1]

The compositions of Examples 1 to 6 and Comparative Example 1 were prepared and evaluated as shown in the following table. The compound (A1) to the compound (A6) obtained in each of Examples 1 to 6 were each diluted with propylene glycol monomethyl ether to a solid content of 3 wt%. In Comparative Example 1, the polymer (E1) obtained in Comparative Synthesis Example 1 was diluted with cyclopentanone to 3 wt%. Here, the solid content means a component other than the organic solvent.

The abbreviations used in the following table are as follows.

Compound (a1)

MAH: maleic anhydride

CAH: citraconic anhydride

IAH: itaconic anhydride

Compound (a2)

APTES: 3-aminopropyltriethoxydecane

Organic solvent (B)

PGME: propylene glycol monomethyl ether

CPN: cyclopentanone

[Evaluation of light alignment sensitivity after prebaking]

The composition for photoalignment film of Example 1 was spin-coated at 1,500 rpm for 10 seconds, and a film was formed on a glass substrate (Eagle XG, manufactured by Corning Co., Ltd., 40 mm × 40 mm × 0.7 mm). Next, it was dried at 130 ° C for 5 minutes on a hot plate.

The film thickness of the dried film was measured by a profiler P-16 (manufactured by KLA-Tencor Co., Ltd., surface roughness, fine shape measuring device). The film thickness was 93 nm.

The light irradiated from the ultrahigh pressure mercury lamp was converted into linear polarized light by a filter that cuts off light of 300 nm or less and a wire grid polarizing plate, and the glass substrate coated with the thin film was irradiated with 10 mJ/cm ² (a value at 313 nm).

Next, the polymerizable liquid crystal composition (1) was spin-coated on the substrate at 1300 rpm for 10 seconds, and dried on a hot plate at 80 ° C for 1 minute. After cooling the substrate to room temperature, the light of an ultrahigh pressure mercury lamp of 300 mJ/cm ² (the value at 313 nm) was irradiated, and the polymerizable liquid crystal composition was photocured to fix the alignment.

The substrate after photohardening of the produced polymerizable liquid crystal was sandwiched between two polarizing plates in a cross nicol state, and the backlight was irradiated from below to observe. The minimum exposure amount that can be displayed in the light and dark without the alignment defect (light leakage), that is, "the light alignment sensitivity after prebaking" is 10 mJ/cm ² .

[Evaluation of light alignment sensitivity after post-baking]

The photoalignment film was spin-coated on the glass substrate in the same manner as described above, dried at 130 ° C for 5 minutes, and further baked at 230 ° C for 30 minutes. Thereafter, the light irradiated from the ultrahigh pressure mercury lamp is converted into linearly polarized light by passing through a filter that cuts off light of 300 nm or less and a wire grid polarizing plate, and is irradiated to the film-coated film at 10 mJ/cm ² (value at 313 nm). glass substrate.

Next, the polymerizable liquid crystal composition (1) was spin-coated on the substrate at 1300 rpm for 10 seconds, and dried on a hot plate at 80 ° C for 1 minute. After cooling the substrate to room temperature, the light of an ultrahigh pressure mercury lamp of 300 mJ/cm ² (at a value of 313 nm) was irradiated, and the polymerizable liquid crystal composition was photocured to fix the alignment.

The substrate on which the produced polymerizable liquid crystal was immobilized was sandwiched between two polarizing plates in a cross nicol state, and the backlight was irradiated from below to observe. The minimum exposure amount that can be displayed in the light and dark without the alignment defect (light leakage), that is, "the light alignment sensitivity after post-baking" is 10 mJ/cm ² .

[Substrate adhesion]

The cross-cut test was performed using the substrate after the polymerization liquid crystal immobilization prepared in the evaluation of the optical alignment sensitivity described above. After the pre-baking, the substrate after the photo-alignment sensitivity test and the substrate after the post-baking photo-alignment sensitivity test were not peeled off in all of the 100 pieces after the tape was peeled off.

Further, in the second to sixth embodiments and the comparative example 1, the same evaluation as in the first embodiment was carried out. The results are shown in Table 2 together with the results of Example 1. In Comparative Example 1, the light alignment sensitivity after prebaking was good, but the light alignment sensitivity after post-baking was remarkably lowered, and the substrate adhesion was also ×. Further, in Comparative Example 1, since it was insoluble in propylene glycol monomethyl ether as an alcohol solvent, it was evaluated using cyclopentanone having a strong dissolving power.

[Industrial availability]

The photo-alignment film of the present invention is excellent in adhesion to a substrate, and is soluble (non-invasive) The alcohol-based solvent that etches the flexible substrate can be produced at low cost, and thus can be used as a liquid crystal alignment film for a wide range of applications.

Claims (5)

A composition for a photo-alignment film containing at least one acid anhydride (a1) selected from the group consisting of compounds represented by formula (1) and formula (2), and an amine group and an alkoxyalkyl group in the molecule. a compound (A1) obtained by reacting the compound (a2) and an organic solvent (B), or a polymer (A2) obtained by polymerizing the compound (A1) and an organic solvent (B), In the formula, R ¹ , R ² and R ³ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms. The composition for a photo-alignment film according to the above aspect, wherein the acid anhydride (a1) is at least one selected from the group consisting of maleic anhydride, itaconic anhydride, and citraconic anhydride. The photo-alignment film composition according to the above-mentioned item, wherein the compound (a2) having an amine group and an alkoxyalkyl group in the molecule is selected from the group consisting of 3-aminopropyltrimethyl At least one of oxoxane, 3-aminopropyltriethoxydecane, 4-aminophenyltrimethoxydecane, and 4-aminophenyltriethoxydecane. A photo-alignment film produced by using the photocurable composition according to any one of claims 1 to 3. A display element using the light as described in claim 4 Manufactured by an alignment film.